(1) Field of the Technology
The present technology relates to a color image forming apparatus and in particular relates to a color image forming apparatus, such as a copier, printer, facsimile machine or the like, which uses electrophotography as a process of image forming, wherein developer images formed on image bearing members are transferred to a printing medium.
(2) Description of the Prior Art
Recently, in the field of image forming apparatus, there is a common trend toward color configurations, and with the development of color image forming apparatus, an increased number of color image forming apparatus have become used.
In the field of color image forming apparatus, in order to make the apparatus compact and improve the speed of color printing, there have been proposed many kinds of color image forming apparatus using an indirect transfer process in which, by use of an intermediate transfer medium, color separations of image information developed by multiple process printing units are laid one over another on the intermediate transfer medium to form a lamination of developer images (primary transfer) and then the laminated developer images are transferred as a whole (secondary transfer) to recording paper that is conveyed, to thereby form a printed color image of information on the recording paper.
In order to create exact images, high-precision positioning is demanded for the multiple process printing units, intermediate transfer medium and the like of the color image forming apparatus. For this purpose, when the multiple process printing units, intermediate transfer member and the like, are mounted to the apparatus body, these components are generally or in previous practice, positioned with reference to the front and rear frames of the apparatus body.
However, the color image forming apparatus includes such components as the intermediate transfer medium and the like, which need maintenance at a fixed cycle and such components as developing units, which need replacement on demand because consumption of the developer from the developing unit in the color image forming apparatus differs depending on color.
Accordingly, in consideration of maintenance performance and workability, some measures have been contemplated such that the opening through which the developing units are attached is widened or the intermediate transfer medium and the developing units are constructed so that they can be positioned unit by unit relative to the apparatus frame. However, these manipulations exert influence on the strength of the apparatus frame and cause the problem of making the entire apparatus bulky due to increase in volume of each unit.
Under these circumstances, development of the positioning unit that positions and fixes the multiple process printing units, each including an image bearing member or photoreceptor drum, developing unit and the like, as a whole by arranging an openable/closable front cabinet in the body frame of the color image forming apparatus, has been made.
Generally, in the color image forming apparatus using the indirect transfer process, a transfer efficiency as high as 100% cannot be achieved in the primary transfer step in which the developer image is transferred from the photoreceptor drum of the process printing unit to the intermediate transfer medium and in the secondary transfer step in which the developer image is transferred from the intermediate transfer medium to recording paper. Usually, the transfer efficiency in this process roughly falls within a range from 80 to 95%.
For this reason, in order for the developers that have not been transferred from the photoreceptor drums to the intermediate transfer medium and remain on the photoreceptor drums and the developer that has not been transferred from the intermediate transfer medium to recording paper and remains on the intermediate transfer medium, not to exert influence on the next printing operation and degrade the printing quality, various configurations which are adapted to collect the developers left over on the photoreceptor drums and intermediate transfer medium have been proposed (c.f. Patent literature 1: Japanese Patent Application Laid-open 2001-324905, Patent literature 2: Japanese Patent Application Laid-open 2002-14503).
Usually, in the color image forming apparatus using an intermediate transfer medium, waste developer is generated at five places, specifically, on the photoreceptor drums of four colors, yellow, magenta, cyan and black, and on the intermediate transfer medium after secondary transfer, so that cleaning devices are provided for those places so as to collect waste developer.
However, in conventional cleaning devices, the developer conveying paths for conveying the collected leftover developers and the developer collecting container for storage, tend to become bulky, hence this causes the problem of the whole apparatus becoming large-sized.
Further, it is also necessary to provide complicated waste developer conveying paths for collecting these together, which not only enlarges the apparatus and complicates the apparatus configuration but also may cause the problem of the developer scattering inside the machine.